Process for ground consolidation and reinforcement of stressed anchorage piling increasing the load capacity

ABSTRACT

A process and system for ground consolidation and increasing the load capacity of piles wherein the lower end of a bore hole is enlarged upon injection of a high pressure liquid, the pressure of which is periodically varied at a high frequency to cause compression and consolidation of the surrounding ground area and the widening of the lower end of the bore hole. Reinforcing anchorage structure is mounted within the bore hole and embedded within hardened concrete or like material, and a stressing steel rod is fixed to the anchorage and extends upwardly through the bore hole for connection to suitable building support structure mounted at ground level.

United States Patent 1191 Wey 1111 3,742,717 14 1 Jul s, 1973':

[ PROCESS FOR GROUND CONSOLIDATION AND REINFORCEMENT OF STRESSED ANCHORAGE PILING INCREASING THE LOAD CAPACITY [76] Inventor: Gino Wey, Russelsheim/Main,

Germany [22] Filed: June 30,197!

[21] Appl. No.: 158,428

[52] US. Cl 6l/53 .52, 61/36, 61/53.6, I 61/53.62, 61/63 [51] Int. Cl E02d 3/12, E02d 5/42, E02d 5/44 [58] Field of Search 61/53.62, 53.6, 53.52, 6l/53.64, 53.66, 56, 56.5, 36, 63, 39, 53.5

[56] References Cited UNITED STATES PATENTS 3,309,878 3/1967 Lamberton; .L. 6ll53t62 961,492 6/1910 Goldsborough.... 6l/53.6 3,130,552 4/1964 Bodine, Jr 61/36 2,497,377 4 2/1950 Swann et' al. 6l/53.6 3,568,452. 3/1971 Stifler, Jr. 6l/53.6

FOREIGN PATENTS OR APPLICATIONS 1,484,392 6/1969 Gennany 6l/53.6

Primary Examiner-Jacob Shapiro Att0rney-William A. Strauch et al.

[ 5 7] ABSTRACT A process and system for ground consolidation and increasing the load capacity of piles wherein the lower end of a bore hole is enlarged upon injection of a high 19 Claims, 25 Drawing Figures 1/1960 Australia 61/5352' PATENTEI] JUL 3 I975 SHEEI 1 0F 8 GINO WEY By STRAUCH, NOLAN, NEALE, NIES & KURZ Attorneys PATENTEDJuLa I975 sues1 2 or a TILYI' Inventor smo WE! By STRAUCH, NOLAN, NEALE, mas &. mmz

Attorneys PATENTEU JUL 3 i975 Inventor GINO WEY By STRAUCH, NOLAN, NEALE, NIES & KURZ Attorneys PATENTEDJULB ms 3.742.717

sun-:1 u or a Inventor GINO WEY By STRAUCH, NOLAN, NEALE, NIES &-KURZ Attorneys PATENTEE] JUL 3 I975 Inventor smo WEY By STRAUCH, NOLAN, NEALE, NIES -& KURZ Attorneys PATENTEDJUL 3 I975 SHEET 6 0F 8 Inventor GINO WEY By STRAUCH, NOLAN, NEALE, NIES & KURZ Attorneys PAIfNTEflJuLs I975 SHEET 7 BF 8.

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1 m w a W r! Wm V// n //M//// I W Fig. 5H

Inventor GINO WEY By STRAUCH, NOLAN, NEALE, NIES & KURZ Attorneys PATENTED JUL 3 I975 SHEEI 8 BF 8 Inventor GINO WEY 'BY STRAUCH, NOLAN, NEALE, NIES Q KURZ M'LornByu PROCESS FOR GROUND CONSOLIDATION AND REINFORCEMENT OF STRESSED ANCHORAGE FILING INCREASING TIIE LOAD CAPACITY This invention concerns a process and an anchorage reinforcement for ground consolidation and the increase-of load for piles with tensile and compressive stresses and forces by the means of ground injection with vibration using a liquid medium resulting in a compression and consolidation as well as widening of the diameter of the bottom of the piles and thus increasing the admissible load of anchorage and pile. Moreover, the invention concerns a special construction of the reinforcement of piles under tractive 'force and anchorages, permitting on one hand the transmission of heavy load by a small diameter of the shaft, and on the other hand avoiding the appearance of tensile stress in the concrete under full load and therefore preventing the cracking of concrete.

A well known process for ground consolidation and piling, the so called stream-vibration process, uses heavy vibrating aggregates whichare lowered into the ground, water being simultaneously flushed into the a ground by nozzles attached to the aggregates. This process has the disadvantage that it can only be applied with piles of great diameters. For constructions of piles with small diameters it is not economical. Moreover,

not be applied for piles with a shaft of small diameter.

Another process consists in the lowering of bore holes by-boring or ramming, the later placement of reinforcements and the forming of an enlargement of the diameter of the piles by grout-injection under high pressure. This has the disadvantage that only limited enlargement is possible and there is no control of the size of the enlargement. Eventually it is possible that a splitting or cracking of the ground takes place on one side only, and the covering and protection against corrosion of the reinforcement is not permanent and is insufficient. One of these methods provides the screwing of a ramming head to the anchorage reinforcement. Using small diameters a local overstressing of the concrete is possible, but the transmission of the tractive force on the concrete by thehead is insufficient.

Moreover the costs for thefabrication of these heads are relatively high, and without the effect desired. Another disadvantage of this process consists in the inevitable cracking of the concrete and the consequent destruction by corrosion caused by the insufficient transmission of force on the head of the pile and the very high extensibility of the tensile steel.

The invention is based on a process and an anchorage reinforcement where the above mentioned disadvantages are eliminated.

This problem is solved by the process of the invention pressing a liquid medium into the ground, this medium being, on one hand, pressed under application of high pressure, on the other hand exposed to reversing or alternating strokes of pressure of high frequency causing by these means a compression of the ground and a widening of the bore hole and placing in the bore hole, before or after the widening, a stressing reinforcement where, after the hardening'of the injected material, only the bottom and the head of the anchorage in the area of the widening of thc pile are imbedded, whereas the prestressed steel reinforcements in the part of the pile widening as well as in the pile shaft are still free, being surrounded by a protective tube which is provided with a closing seal as well on the bottom of the the anchorage parts extend mainly to the length of the widened shaft, containing the stressing element in a part of the enlarged pile and axial equipment as installation for fixation, stressing, these elements extending axially into the anchorage parts, the anchorage parts carrying on both ends dowels or plugs protruding radially into the enlargement of the pile, one acting against the other axially. This special stressing construction makes it possible, by the underground compression and the widening of the pile formed in this way, to construct a pile or anchorage by means of stressing elements having to carry loads of traction,-the concrete always being exposed to compressive stress, never to tensile stress, and moreover that, by the injection after the building and stressing of the anchorage part, a very safe and strong placement in the ground is obtained.

A number of applications of the invention are explained in detail by the following figures:

FIG. 1 illustrates an apparatus according to the in vention, with ram, pumps, and vibrating aggregates for ground consolidation;

FIG. 2 illustrates the performance of an underground consolidation or widening of the bottom of the pile by a vibrating injection;

FIG. 3 illustrates the bulb of a pile during a vibrating injection;

FIG. 3A is a section along line 3A3A of FIG. 3;

FIG. 4 illustrates completed pile enlargement of the bulb and prestressing reinforcement;

FIG. 4A illustrates an enlargement of the bulb of a completed pile in a modified form of construction of the prestressed reinforcement;

FIG. 48 illustrates an enlargement of the bottom of a completed pile with a third form of construction of the stressing reinforcement;

FIG. 4C is a section according along line 4C4C of FIG. 4B;

FIG. 4D is an enlarged view of the part X of the FIG. 4B;

FIG. 4E is an enlarged view of the part X of the FIG. 4B, in another way of execution;

FIG. 4F is an enlarged view of the bottom of a completed pile in another form of construction;

FIG. 5A illustrates a ram and injecting aggregate for the construction, of piles with vibrating injection, the ram head being removable after lowering the boring set.

FIG. 58, C and D show embodiments in which only ramming'is possible, without telescoping;

FIGS. 5E and F show embodiments in which ramming is possible with telescoping, the head being lost after telescoping;

FIGS. 56, H, I and K show embodiments in which telescoping is possible, as well as removing the ram head;

FIG. SL is a section on line L5L of FIG. 5K;

FIG. 6 is a diagrammatic view of vibration'injection of the bottom of the pile, using a folded bag or hose with a back flow and an energy absorber;

FIG. 7 shows apparatus for vibration injection, according to FIG."6, but without back flow, onthe other hand with circulating flow; and v FIG. 7A is a section along lines 7A7A of FIG. 7.

The process, according to the invention, allows sink-- ing a bore hole into the ground by boring, ramming, or

with water using very fine aggregates, as argillaceous materials, fly ash, etc., in order to close pores and voids in the ground, and subsequently injecting hardening materials, or onlythe latter. The placement of the reinforcement is .either carried out before the first or before the second vibration injection with grout or hardening material.

. In case ofsoil with very fine aggregates, e.g. argillaceous material, a previous compression with water is not to be recommended because this can lead to formations of slurry and mud. For this case the invention provides the placement of a folded bag or hose into the bore hole, with subsequent vibrating injection of the bag, so that the liquid does not touch the soil. Subsequently, the reinforcement is placed, and another vibrating injection with grout or hardening material can take place.

In case of piles under tractive force and having a shaft of small diameter through which the reinforcement has to be placed the invention provides, for a transmission of the very high tractive forces, in order to avoid cracking of the concrete and for protection against corrosion of the steel, the following construction of the anchorage: The bottom of the anchorage is reinforced by additional steel reinforcements, so that on one hand the stress in the steel isreduced, and on the other hand, the elongation'and inclination to form cracks is diminished. These steel reinforcements, in form of a basket or a cone, are attached-to the central vided with plates or rings in form of dowels or plugs, or

a spirally rolled reinforcement of great diameter, so

that a transmission of the whole tractive load at the bottom of the pile occurs. In the medium part of the enlarged bottom of the pile the tie'rods are surrounded by a protective tube which has, at the bottom, a tight seal, and on the top, at the passage into the narrow shaft, a tight closing plate. By this arrangement it is possible to inject first the enlarged bottom of the pile with the anchorage alone whereas thesteel tie rods in the central protective tube are still free, i.e.not yet surrounded with grout or hardened material. J

After the hardening the bulb of the pile can be prestressed, and after the fastening on the completed building and the application of the provided load it is possible to inject the voids between the tie rods and-the protective tube and shaft of the pile with hardening material. By this method tensile stresses in the concrete are either completely avoided or reduced to a minimum. If necessary, it is also possible to "overstress the tie rods, i.e. to apply a higher stress than is to be expected and after the injection of the tie rods, tubes and the shaft of the anchorage to discharge again, so that this part obtains a certain prestress.

Finally, the process provides a certain construction of the ramming aggregates, so that on one hand, when ramming, the ram heads, or boringcutters can be re gained, on the other hand a telescoping is possible.

In FIG. 1 is shown the sinking ofa boring I by driving a boring tube 2 with a ram head 3 with flushing channels 3a which are connected by a flushing tube 4 and a flushing head 5 fixed to the boring tube 2 and connected with a pump 6. On the pressure pipe 5a is fixed a vibration device 7 with a membrane 8, piston 9 and eccentric wheel 10, similar to a membrane pump; the form of the'eccentric wheel is constructed according to the desired acceleration curve of increase of fluid pres-.

110 is attached a vibrating device. 14 with a piston 15 and a vibrator 16. If necessary, it is possible to connect rod or rods of steel by welding or screwing, being proa second vibrator device 17 with a piston 18 which is,

driven by a link 19 and a driving'disk 20, i.e. the strokes of compression can be produced by several vibrators, the amplitude and frequency being variable according to the local soil conditions. The ramming of the boring tube 2 is carried out by theram 21 which is appropriately'prov-ided with an arrangement for ramming and rotating. The boring tube 2 has also apertures 22 and 25 for flushing and injecting. Opening and closing of these apertures is operated by rnutual displacement of the tubes 2 and 4 and, in connection therewith, the displacement of the slides 23 and 26, i.e. the ram head 3.

Simultaneously it is possible to arrange apertures, e.g. in the ram head with contractions 24 in order to divertthe flow of water and to increase the velocity at the outlet. In this case the process of the enlargement of the bottom of the hole 27, whereas, e.g., an injection 'carried out as well as with one. or the other system and while running or also during withdrawing the tubes.

FIG. 3 shows-a tractive pile with prestressing reinforcement during the vibration injection. FIG. 4 represents a completed pile. At first there is placed into the bore hole the tie rod 30 it. is possible to use only one, or several rods), carrying bottomof the anchorage 3 1, protective tube 34, head plate-37, and stressing head 45. The bottom of the anchorage consists of a reinforcement with several longitudinal irons 32, to which are attached circles or plates 33a-d, or an additional spiral reinforcement. The connection of the bottom of the anchorage, i.e. the reinforcement with the tie rod 30 can be made by welding, screwing, or mechanical joint.

Above the bottom of the anchorage 31 the tie rod is leadstressing channel 34a. At the upper end ofthe bulb i.e.

the enlargement of the pile hole, is placed an additional reinforcement, consisting of several plates 38 with vertical ribs 39 near or below the head plate 37 carrying stressing head 45. Moreover, in the stressing head 45, which is shaped on the outside in form of a cylinder, on the inside in form of a cone, there are placed several wedges 46, showing .on the outside one or several spaces 47, throughwhich, during the injection of the stressing channel 340, the grout can pass. Simultaneously with the reinforcement a packing collar or obturator is introduced, being joined to the headingplate 37. This obturator is used in order to obtain a tight seal between the lower enlargement of the pile hole 48 and the narrow shaft of the pile. This can be operated by applying an elastic tightening ring 42 on top of the head plate 37 which is axially squeezed by ring 43 by the auxiliary. tube 44, and consequently pressed against the outside boring hole i.e. casing tube 2.

After this operation the injection of the outside bottom of the pile with grout through the injection tube 40 takes place, during which process another enlargement of the bottom of the pile hole by vibration with the vibrators 7, l4, or 17, as shown in FIG. 1 can be carried out. If necessary, an additional protection against corrosion of the anchorage 31 by placing a bell-shaped tube with apertures for the flow of grout can be obtained.

After the hardening of the grout in the bulb 48 a prestressing of the anchorage 31 and a fixation with wedges 46 can be carried out. Then a protective tube 49 in the shaft of the pile above the stressing head 45/46 and the tie rod 30 is placed as shown in FIG. 4. After fixing or connecting the pile with the building 52, Le. with the steel girders 53, bearing plates 54, and

screw 55, a repeated stressing of the tie rod 30 is carried out, with a subsequent injection of the stressing channels 34a and 50, as well as the shaft of the pile 51. The injection of the stressing channel 34a can also be carried out during the first stressing of the anchorage. Instead of the ribs 39 shown in FIG. 3 it is possible to fix wires or pins .to the rings 38 and the head plate 37, building a power transmission between the different plates or rings 38 andthe respective head plate 37 in the axial direction.

FIG. 4A shows a prestressed concrete pile, along the lines of FIGS. 3 and 4, but with the upper and lower anchorages protected continuously against corrosion, as by bell shaped enclosures 40 and head plate 56 being threadedly attached to the lower end of tie rod 30. The same constructions of anchorage and-stressing head are employed at the upper and'lower parts of the widened pile hole.

The example of FIGS. 48 and 4C represents the end range of the anchoragepart surrounded by a mainly cylindrical retaining wall 101 for protection against corrosion. The plate-shaped or disk-shaped dowel elements 102 have mainly the same diameter as the closing plate 56. The cylindrical wall for protectionag'ainst corrosion 101 forms a space between the outside border of the disk dowels 102 in order to enable the injection of the inside part of the cylindrical wall 101 with binding material. The cylindrical wall 101 is fixed to the closing plate and the inside dowel 2 by means of ridges 103. In the same way as shown in FIG. 4A,

there are fixed vertical ribs 39 between the dowel plates 102. As the same time the ribs 39 extend radi- Y ally, wires or pins can be fixed at intervals instead to the dowel plates 102 on the outside periphery building a power transmitting connection between dowel plates 102 in axial direction. By the cylindrical wall 101 the access of humidity through the concrete to the covered part of the anchorage and, above all, the access of humidity to the stressing element 30 is prevented or at least greatly reduced. Besides, the wall 101 fastens the inside concrete block radially and prevents a cracking or destruction of the concrete under the influence of the very high forces and stresses transmitted by the dowel plates 102 to the concrete.

Examples for an appropriate construction of the cylindrical wall 101 are shown in FIGS. 4D and 4E. According to FIG. 4D, the cylindrical wall 101 consists of a steel plate or sheet corrugated in the direction of the periphery, in order to form a better connection with the widened part of the pile. The steel sheet 104 is covered, at least on the outside, of the cylindrical wall 101, better on .both surfaces, with synthetic material 105, in order to be itself protected against corrosion.

- In the example of FIG. 4E, the cylindrical wall is formed by a steel wire spiral 106. This steel wire'spiral 106 is covered with synthetic material 117,- which is fixed in such a way that the voids or spaces between the windings are closed and therefore form an entire cylindrical wall. Besides these examples, any other construction of the cylindrical wall 101 is possible, if this wall possesses sufficient stability and resistance against corboring hole, rods or plates 108, pivoted on the protective tube 34, linked together and remaining in a fixed position, as shown in FIG. 4F, are arranged in such a way that during the introduction of the stressing reinforcement they lean against the outside part of the protective tube 34. As soon as the anchorage part reaches the enlarged part of theboring, the dowels 108 move under the influence of the gravity or under the influence of applied readjusting springs into the holding position.

FIGS. 5A-5L shows another arrangement for the lowering of the pile and the execution of the vibrating injection, wherein the boring heads or boring cutters can be regainedafter the lowering. This arrangement also allows telescoping. The ram is placed on the inside tube 64, which stands out above the casing tube a, 60b, and 60c. The respective tubes are provided with flushing heads Her and connected in the upper part by a flange, if necessary screwed one to the other.

The construction in FIG. 5A shows a tube 60a, with a strengthening of the wall and with athread 62 on the lower part, whereas on the head a suitable thread is applied, so that the head and the tube 60a can be screwed one to the other. When using a construction according to FIG. 5B, the casing tube 60b is strengthened in the lower-part and shows a conical contraction 67 the head 66b on the outside having a suitable conical shape.

FIG. 5C presents the constructionof a casing tube with a step or a contraction, the head 66c resting on this step.

V FIG. D shows the arrangement of a ring 68 or an alternative ring 69 below the boring tube 60, this ring surrounding the outside part of the boring tube 60, the

boring tube 60 and the head 66d or 66:12 resting on this ring 68 resp. 69 (68, 66bl= construction with step; 69, 66b2= construction with a conical connection).

FIGS. 5E and 5D show the arrangements during the pulling out of the head with the interior tube and then the casing tube 60.

FIG. SF shows the head 66f with circular support 70 or 71 (70 with the same diameter as the casing tube 60, 71 with a greater diameter as the casing tube 60). I FIG. 5G shows the head 66g with wedge 74 between the casing tube 60 and head 66g, as well as circular support 73 arrangement of ring and wedge in one piece 72.

FIG. 5H shows the head 66h and a twinwedge 75/76 allowing a telescopic lowering, both wedges being removed before telescoping or a head 66g with twinwedge 76/77 and circular support 78.

FIG. SI shows the same construction as FIG. 5H, after telescoping, an additional casing tube 79 with wedges 80 having been introduced.

In order to be able to pierce stones or rock, the ramming head 66 and the outside casing tube 60 are to be provided with hard metal cutters 81.

FIG. 5K shows an arrangement where the interior boring tube 64K above the inset in the head has a conical sloping, wedges 82 being introduced between the boring tubes 64K and 60 provided with cams 83, catching the head 66K. These wedges 82 are pressed upon the exterior casing tube 60 by screwing the interior tube 64K with the head 66K. Removing the head 66K this is held by.a face spanner, while the tube between the wedges, and the inside tube 64K is screwed out for a few turns.

Besides the possibilities shown in FIGS. SA-K there are other combinations of these cases appliable which are, however, not presented for reasons of clearness.

FIG. 6 represents a vibrating injection using a closed and folded bag or hose 90, fixed to the pressure pipe 91. The packing collar 92 is used in order to obtain a tight seal between the casing tube 60 and the pressure pipe 91. Besides there is attached a tube for the back flow 93 from the bag 90, leading into the casing tube 60, and from there to an energy absorber 94 with an exit valve 95. The energy absorber can also be constructed in another way and is only presented schematically.

FIG. 7 shows an arrangement like FIG. 6, but without a reflow tube, in the center of the bag 90 a tube 96 being placed, containing a propeller 97 with a driving engine, causing a circulation of the liquid put under pressure which is derived by a casing 98. After the widening of the bore hole, the bag is emptied and removed from the bore hole. In order to reduce the damping of the vibration by the tubes, it is possible to place the vibrating aggregates 7, 14, or 17 into the boring tube, in case of necessity the boring tube being widened in the upper part.

I claim:

1. Process for ground consolidation and increasing the load capacity of piles and tractive anchorages after the forming of a bore hole in the ground, characterized by the injection of a liquid medium into the ground at the lower part of said hole, said liquid medium being injected under a high pressure which is periodically varied at high frequency to cause a compression and consolidation of the ground and a widening of the bore hole below ground level, said liquid medium being provided by two injection systems one of which injects liq uid through a bore hole forming ram head having injection channels and the other of which injects liquid through apertures in an outside casing tube within the bore hole, placing a stressing reinforcement anchorage within the hole, and introducing pile forming material into the bore, the anchorage within the widened pile hole portion being imbedded in the hardened pile forming material.

2. Process according to claim 1 characterized by selectively opening the injection apertures in the casing tube such opening being caused by mutual displacement of the casing tube and an inside boring injection tube.

3. Process according to claim 2, characterized by rotating the tubes around their longitudinal axes during ramming and liquid injection.

4. A method of ground consolidation and forming piles of increased load capacity that comprises the steps of injecting into the lower end of a bore formed in the ground a liquid medium under pressure and during injection varying the pressure of said liquid medium at a predetermined frequency for effecting widened enlargement of the lower end of said bore, said liquid medium being provided by two injection systems one of which injects liquid through a bore forming ram head having injection channels and the other of which injects liquid through apertures in an outside casing tube within the bore.

5. The method defined in claim 4, wherein a reenforcement anchorage is introduced into the bore in such location as to be disposed within said widened lower end of the bore, and introducing into said bore fluid concrete or like pile material for hardening in situ around said anchorage.

6. The method defined in claim 5, wherein said reenforcement anchorage comprises a steel structure and the method includes the step of prestressing said structure.

7. The method defined in claim 6, wherein grouting is injected into the wall of the widened lower end of the bore after prestressing of the anchorage and prior to introduction of said pile forming material.

8. A system for providing piles of increased load capacity comprising a boring tube having a ram head at its lower end and a reciprocable ram connected to its upper end to said boring tube for driving said ram head into the ground to form a bore hole, means providing a source of liquid under pressure and including means independent of said ram for periodically varying said pressure, liquid discharge passages in said ram head, and means connecting said source to said passages whereby liquid at pulsating pressure may be injected into the lower end of the bore hole formed by said ram head for widening said lower end of the bore hole.

9. The system defined in claim 8, wherein said source comprises a pump for delivering liquid to a line at a predetermined pressure and said pressure varying means comprises a cyclically operable pump connected to said line and operable independently of said ram for periodically increasing said predetermined pressure at relatively high frequency.

10. The system defined in claim 8, wherein said ram head is detachably connected to said boring tube and said means for providing a source of liquid under presboring tube to said ram head.

11. The system defined in claim 8, wherein said boring tube is formed with lateral apertures above its connection to said ram head, and means is provided for connecting a second source of liquid for discharging liquid at high pressure with high frequency pulsation through said apertures for further widening the lower end of said bore hole.

l2.-The system defined in claim 8 comprising an anchorage structure in the form of assembled metal reenforcement elements to be embedded within the pile mounted within the lower part of said bore hole so as to be disposed at the widened region in said bore hole.

13. The system defined in claim 12, wherein said anchorage is introduced through the boring tube after said tube has been withdrawn from the widened lower end of the bore hole.

14. The system defined in claim 12 comprising means for prestressing said anchorage prior to introduction of hardening concrete or the like within the widened lower end of said bore hole.

15. The system defined in claim 12, comprising at' least one tie rod extending the length of said bore hole and fixed at its lower end to said anchorage structure, a protective tube surrounding the lower end of said rod within the widened lower end of the bore hole, means closing the lower end of said protective tube near the anchorage structure, a stressing head secured to said rod near the upper end of said protective tube, and means providing a seal between the protective tube and the boring tube.

16. The system defined in claim 15, comprising 4 the bore hole.

17. System defined in claim 16 wherein a second anmeans for introducing grouting through the stressing head for lining the wall of said widened lower part of 18. A system for ground consolidation and increasing the load capacity of piles and tractive anchorages after sinking a bore hole, comprising means for injecting a liquid medium into the ground at the lower end of the bore hole, said liquid medium being injected under high pressure which is periodically varied at high frequency to cause a compression and consolidation of the ground and a widening of the lower end of the bore hole, an anchorage in the form of a stressing reinforcement adapted to be disposed within said bore hole and to be imbedded within hardened concrete or like material filling the lower end of said bore hole, at least one stressing steel rod fixed to said anchorage and extending substantially the length of the bore hole and its widened lower end, and a protective tube surrounding said rod and provided with a tight seal at the bottom of the anchorage.

19. System as defined in claim 18, further comprising an outer casing tube extending down the'bore hole an inner tube extending down through said casing tube, and means for detachably securing a ram head to said tube, said inner tube being connected to receive said pressurized liquid medium, and said ram head being formed with discharge passages for said liquid medium.

III IR 

1. Process for ground consolidation and increasing the load capacity of piles and tractive anchorages after the forming of a bore hole in the ground, characterized by the injection of a liquid medium into the ground at the lower part of said hole, said liquid medium being injected under a high pressure which is periodically varied at high frequency to cause a compression and consolidation of the ground and a widening of the bore hole below ground level, said liquid medium being provided by two injection systems one of which injects liquid through a bore hole forming ram head having injection channels and the other of which injects liquid through apertures in an outside casing tube within the bore hole, placing a stressing reinforcement anchorage within the hole, and introducing pile forming material into the bore, the anchorage within the widened pile hole portion being imbedded in the hardened pile forming material.
 2. Process according to claim 1 characterized by selectively opening the injection apertures in the casing tube such opening being caused by mutual displacement of the casing tube and an inside boring injection tube.
 3. Process according to claim 2, characterized by rotating the tubes around their longitudinal axes during ramming and liquid injection.
 4. A method of ground consolidation and forming piles of increased load capacity that comprises the steps of injecting into the lower end of a bore formed in the ground a liquid medium under pressure and during injection varying the pressure of said liquid medium at a predetermined frequency for effecting widened enlargement of the lower end of said bore, said liquid medium being provided by two injection systems one of which injects liquid through a bore forming ram head having injection channels and the other of which injects liquid through apertures in an outside casing tube within the bore.
 5. The method defined in claim 4, wherein a reenforcement anchorage is introduced into the bore in such location as to be disposed within said widened lower end of the bore, and introducing into said bore fluid concrete or like pile material for hardening in situ around said anchorage.
 6. The method defined in claim 5, wherein said reenforcement anchorage comprises a steel structure and the method includes the step of prestressing said structure.
 7. The method defined in claim 6, wherein grouting is injected into the wall of the widened lower end of the bore after prestressing of the anchorage and prior to introduction of said pile forming material.
 8. A system for providing piles of increased load capacity comprising a boring tube having a ram head at its lower end and a reciprocable ram connected to its upper end to said boring tube for driving said ram head into the ground to form a bore hole, means providing a source of liquid under pressuRe and including means independent of said ram for periodically varying said pressure, liquid discharge passages in said ram head, and means connecting said source to said passages whereby liquid at pulsating pressure may be injected into the lower end of the bore hole formed by said ram head for widening said lower end of the bore hole.
 9. The system defined in claim 8, wherein said source comprises a pump for delivering liquid to a line at a predetermined pressure and said pressure varying means comprises a cyclically operable pump connected to said line and operable independently of said ram for periodically increasing said predetermined pressure at relatively high frequency.
 10. The system defined in claim 8, wherein said ram head is detachably connected to said boring tube and said means for providing a source of liquid under pressure comprises a conduit extending down within said boring tube to said ram head.
 11. The system defined in claim 8, wherein said boring tube is formed with lateral apertures above its connection to said ram head, and means is provided for connecting a second source of liquid for discharging liquid at high pressure with high frequency pulsation through said apertures for further widening the lower end of said bore hole.
 12. The system defined in claim 8 comprising an anchorage structure in the form of assembled metal reenforcement elements to be imbedded within the pile mounted within the lower part of said bore hole so as to be disposed at the widened region in said bore hole.
 13. The system defined in claim 12, wherein said anchorage is introduced through the boring tube after said tube has been withdrawn from the widened lower end of the bore hole.
 14. The system defined in claim 12 comprising means for prestressing said anchorage prior to introduction of hardening concrete or the like within the widened lower end of said bore hole.
 15. The system defined in claim 12, comprising at least one tie rod extending the length of said bore hole and fixed at its lower end to said anchorage structure, a protective tube surrounding the lower end of said rod within the widened lower end of the bore hole, means closing the lower end of said protective tube near the anchorage structure, a stressing head secured to said rod near the upper end of said protective tube, and means providing a seal between the protective tube and the boring tube.
 16. The system defined in claim 15, comprising means for introducing grouting through the stressing head for lining the wall of said widened lower part of the bore hole.
 17. System defined in claim 16 wherein a second anchorage comprising an assembly of metal reenforcement members is mounted on the bottom of the stressing head and within said widened lower portion of the bore hole.
 18. A system for ground consolidation and increasing the load capacity of piles and tractive anchorages after sinking a bore hole, comprising means for injecting a liquid medium into the ground at the lower end of the bore hole, said liquid medium being injected under high pressure which is periodically varied at high frequency to cause a compression and consolidation of the ground and a widening of the lower end of the bore hole, an anchorage in the form of a stressing reinforcement adapted to be disposed within said bore hole and to be imbedded within hardened concrete or like material filling the lower end of said bore hole, at least one stressing steel rod fixed to said anchorage and extending substantially the length of the bore hole and its widened lower end, and a protective tube surrounding said rod and provided with a tight seal at the bottom of the anchorage.
 19. System as defined in claim 18, further comprising an outer casing tube extending down the bore hole an inner tube extending down through said casing tube, and means for detachably securing a ram head to said tube, said inner tube being connected to receive said pressurized liquid medium, and said ram head being formed with discharge passages for said liquid medium. 